It is known in the prior art to provide passive seat belt systems in which a seat belt is constructed and arranged to be anchored at one end to a retractor mechanism on the vehicle floor inboard of a vehicle seat and at its other end to a vehicle door. When the vehicle door is in closed position, the belt extends diagonally from the retractor mechanism over the upper torso of the seat occupant to the door anchor point. When the door is opened, the upper end of the belt is swung outwardly with the door away from the seating position to provide ease of egress or ingress. Reference may be made to U.S. Pat. No. 3,931,988 issued Jan. 31, 1976 to Klaus Oehm et al. for a "Vehicle Safety Device" for a disclosure of such a passive restraint system in its simplest form.
In a more complex form, a belt or belts may be connected to cables actuatable by motor driven pulleys mounted within the door. The pulley systems are operable to automatically position the belt or belts about the seat occupant when the latter sits down and then closes the adjacent vehicle door. Upon the door being opened, the belt is automatically retracted to a position providing for greater ease of egress or ingress. Such a system is exemplified in U.S. Pat. No. 3,882,955 issued May 13, 1975 to Yuichiro Kaneko et al. for a "Safety Belt Device for Vehicles".
There are significant objections to the passive seat belt systems exemplified by the cited patents. In the system disclosed in U.S. Pat. No. 3,931,988, the vehicle door to which the upper end of the belt is anchored must be framed and reinforced to absorb any load placed on the door frame by the belt, as might occur during an accident. As a result, the vehicle body style cannot be a popular hardtop version that was in vogue several years ago since the doors of a hardtop sedan are frameless above the vehicle belt line. Also, the drag of the belt as it is protracted and retracted results in a noticeable increase in door opening effort.
The system disclosed in U.S. Pat. No. 3,882,955 also requires a framed door, and further requires a rather complex door structure below the belt line to accommodate the motors, pulleys, cables and the like used in the power system. The packaging of these items, plus the latch mechanisms, window regulators, window glass and safety beams that must be housed between the inner and outer door panels, present greater difficulty.
It has been suggested that a power operated system for shifting the belt upper anchor point to provide easier egress and ingrees from and to the seating position be mounted in the vehicle roof structure, see U.S. Pat. No. 4,061,365 issued Dec. 6, 1977 to Toshio Nagano et al. for a "Saftey System for Protection of Automotive Seat Occupant." The disclosed power system utilizes a reversible electric drive motor and a complex control circuit for controlling the motor to move the belt along a guide rail mounted in proximity to the vehicle roof rail at the vehicle side adjacent the outboard side of the seating position.
According to the present invention, the seat belt is anchored at its upper outboard end in the vehicle roof rail structure and utilizes the motion of the door to energize the belt system to automatically draw the seat belt from the door opening to provide unobstructed entry room. The system, however, uses no electric, or other motors, for its power and, therefore, requires no complex electrical, hydraulic or vacuum circuits to energize the system.